java - 我的方法输出错误 : java. util.InputMismatchException

Question

首先，我已经说过我对这一切都是新手，所以请对我宽容点。

我收到了一项任务，要创建一个名为 loadLeague() 的方法，尽管我付出了一切努力，但事实证明该方法进展相当困难!我想知道你是否能帮助我。任务本身是关于足球联赛表的。我的方法编译没有任何问题，但随后它在 Main (或任何其他标准输出)上输出“InputMismatchException”错误。我简直要把我的头发扯下来(好吧，还剩下什么)，我想知道我做错了什么，因为我已经读完了所有关于 Java 的书!各位可爱的专家能否看看我下面的代码并指出我正确的方向？

谢谢大家!!

附注我只是想对这个论坛表示感谢，因为它帮助我找到了第一份真正的 IT 工作。我很少在这里发表评论或提出问题，但我每天晚上都会阅读其他人提出的评论和问题，这些对我的面试确实有帮助。非常感谢!

import java.io.*;
import java.util.*;

/**  
 * Class League - An instance of this class represents the teams in a
 * football (or similar) league. It provides a class method for creating
 * a new instance of League by reading the data for the teams from a CSV
 * file.
 * 
 * @author Lewis Jones 
 * @version 1.0
 */

public class League
{
   /* instance variables */
   private String name;  // The name of the league
   private Team[] teams; // An array to hold the teams in the league

   /**
    * Constructor for objects of class League. It sets the name of the league
    * to the String object provided as the first argument and initialises teams
    * to an array of the size provided as the second argument. This constructor 
    * is private as it is intended for use only by the class method loadLeague().
    */
   private League(String aName, int size)
   {
      super();
      this.name = aName;
      this.teams = new Team[size];
   }

   /* class method */
   /**
    * This method creates a new League object by reading the required details from
    * a CSV file. The file must be organised as follows:
    *     name(String), number of teams (int)
    *     team name(String), won(int), drawn(int), lost(int), for(int), against    (int)
    *        and so on for each team
    * Having created the new League object the method should create all the Team 
    * objects (using the data in the file to set their attributes) and add them 
    * to the teams array.
    */
   public static League loadLeague()
   {
      League theLeague = null;
      String pathname = OUFileChooser.getFilename();
      File aFile = new File(pathname);
      Scanner bufferedScanner = null;

      try
      {
         String leagueName;
         int numberOfTeams;

         String teamName;
         int won;
         int drawn;
         int lost;
         int goalsFor;
         int goalsAgainst;
         Scanner lineScanner;
         String currentLine;
         bufferedScanner = new Scanner(new BufferedReader(new FileReader (aFile)));    

         while (bufferedScanner.hasNextLine())
         {
            currentLine = bufferedScanner.nextLine();
            lineScanner = new Scanner(currentLine);
            lineScanner.useDelimiter(",");

            leagueName = bufferedScanner.next();
            numberOfTeams = bufferedScanner.nextInt();

            teamName = bufferedScanner.next();
            won = lineScanner.nextInt();
            drawn = lineScanner.nextInt();
            lost = lineScanner.nextInt();
            goalsFor = lineScanner.nextInt();
            goalsAgainst = lineScanner.nextInt();

            Team aTeam = new Team(lineScanner.next());
            aTeam.setWon(lineScanner.nextInt());
            aTeam.setDrawn(lineScanner.nextInt());
            aTeam.setLost(lineScanner.nextInt());
            aTeam.setGoalsFor(lineScanner.nextInt());
            aTeam.setGoalsAgainst(lineScanner.nextInt());
            Team[] teams = new Team[numberOfTeams];
            teams[numberOfTeams] = aTeam;
            numberOfTeams++;
            theLeague = new League(leagueName, numberOfTeams);
         }
      }  
      catch (Exception anException)
      {
         System.out.println("Error: " + anException);
      }
      finally
      {
         try
         {
            bufferedScanner.close();
         }
         catch (Exception anException)
         {
            System.out.println("Error: " + anException);
         }
      }
      return theLeague;
   }

   /* instance methods */

   /**
    * Displays the league table in tabular format to the standard output
    */
   public void display()
   {
      System.out.println(this.name);
      System.out.format("%20s %2s %2s %2s %2s %2s %2s %    2s\n","","P","W","L","D","F","A","Pt");
      for (Team eachTeam : this.teams)
      {
         System.out.format("%20s %2d %2d %2d %2d %2d %2d %2d\n",
                       eachTeam.getName(), eachTeam.getPlayed(), 
                       eachTeam.getWon(), eachTeam.getDrawn(), 
                       eachTeam.getLost(),eachTeam.getGoalsFor(), 
                       eachTeam.getGoalsAgainst(), eachTeam.getPoints());        
      }
   }

   /**
    * Arrange the elements of teams in their natural order. This will only
    * work if a natural order has been defined for the class Team.
    */
   public void sort()
   {
      // to be written later...
   }
}

编辑:下面是此任务附带的示例(输入)文件。我很抱歉。我昨晚完全忘记将其包含在我的帖子中。

Scottish League Division 1,10
Airdrie United ,3,2,11,14,25
Clyde          ,5,7,4,21,17
Dundee         ,7,2,7,21,18
Gretna         ,10,3,3,43,20
Hamilton Acas  ,7,5,4,19,20
Livingstone    ,6,6,4,21,15
Partick Thistle,8,4,4,25,29
Queen of South ,3,3,10,11,31
Ross County    ,4,4,8,14,24
St Johnstone   ,6,6,4,26,16

Answer 1

我很清楚问题出在哪里。您的输入文件格式不正确。例如，当您期待“int”时，您正在读取不同的格式，例如字符串。由于我没有您的输入，这里有一个简单的示例来向您展示如何生成该异常:

示例文件包含以下行:

示例.txt
1,8,6,3
1,2,无效,3

正如您将看到的，由于第二行生成错误，因此仅打印 Sample.txt 的第一行。输出:
1、8、6、3

Exception in thread "main" java.util.InputMismatchException
    at java.util.Scanner.throwFor(Scanner.java:909)
    at java.util.Scanner.next(Scanner.java:1530)
    at java.util.Scanner.nextInt(Scanner.java:2160)
    at java.util.Scanner.nextInt(Scanner.java:2119)
    at staxpro.StAXPro.main(StAXPro.java:35)

public static void main(String[] args) {
        try {
            Scanner bufferedScanner = new Scanner(new BufferedReader(new FileReader ("Sample.txt")));
            while (bufferedScanner.hasNextLine()) {
                String currentLine = bufferedScanner.nextLine();
                Scanner lineScanner = new Scanner(currentLine);
                lineScanner.useDelimiter(",");

                int first = lineScanner.nextInt();
                int second = lineScanner.nextInt();
                // Here is where I read a string than an int value
                // on the 2nd line of the input file
                int third = lineScanner.nextInt();
                int forth = lineScanner.nextInt();


                System.out.println(first + ", " + second + ", " + third + ", " + forth);
            }
        } catch (FileNotFoundException ex) {
            System.err.println(ex.getLocalizedMessage());
        }
    }

编辑:

快速查看您的代码+输入文件，我发现了另一个问题:

teamName = bufferedScanner.next();
            won = lineScanner.nextInt();
            drawn = lineScanner.nextInt();
            lost = lineScanner.nextInt();
            goalsFor = lineScanner.nextInt();
            goalsAgainst = lineScanner.nextInt();

            Team aTeam = new Team(lineScanner.next());
            aTeam.setWon(lineScanner.nextInt());
            aTeam.setDrawn(lineScanner.nextInt());
            aTeam.setLost(lineScanner.nextInt());
            aTeam.setGoalsFor(lineScanner.nextInt());
            aTeam.setGoalsAgainst(lineScanner.nextInt());

你能发现它吗？您读取 #wins、#drawns 等，并将它们存储在 won、drawn、lost、goalsFor 中strong>、goalsAgainst，但是当您要创建 Team 对象时，您将从扫描仪中读取 NEXT 值。所以基本上，你总是会每隔一行阅读!!删除所有内容，但保留此部分:

        Team aTeam = new Team(lineScanner.next());
        aTeam.setWon(lineScanner.nextInt());
        aTeam.setDrawn(lineScanner.nextInt());
        aTeam.setLost(lineScanner.nextInt());
        aTeam.setGoalsFor(lineScanner.nextInt());
        aTeam.setGoalsAgainst(lineScanner.nextInt());

因此，根据上述内容，在您的输入文件中，每一行必须具有:字符串、int、int、int、int、int
但如果您注意到，输入文件的第一行是:

Scottish League Division 1,10

这是一个字符串、int、int。解决这些问题，你就可以开始了。这只是我的观察，尚未实际运行您的代码。所以我可能会错过一些东西。如果修复这些问题后仍然存在问题，请告诉我。

编辑(2):
我修改了你的代码并进行了更正。我针对此输入运行了它:

Scottish League Division 1,10
Airdrie United ,3,2,11,14,25
Clyde          ,5,7,4,21,17
Dundee         ,7,2,7,21,18
Gretna         ,10,3,3,43,20
Hamilton Acas  ,7,5,4,19,20
Livingstone    ,6,6,4,21,15
Partick Thistle,8,4,4,25,29
Queen of South ,3,3,10,11,31
Ross County    ,4,4,4,14,24
St Johnstone   ,6,6,4,26,16

而且效果很好。如果还有其他问题请告诉我。

import java.io.*;
import java.util.*;

/**  
 * Class League - An instance of this class represents the teams in a
 * football (or similar) league. It provides a class method for creating
 * a new instance of League by reading the data for the teams from a CSV
 * file.
 * 
 * @author Lewis Jones 
 * @version 1.0
 */

public class League
{
   /* instance variables */
   private String name;  // The name of the league
   private Team[] teams; // An array to hold the teams in the league

   /**
    * Constructor for objects of class League. It sets the name of the league
    * to the String object provided as the first argument and initialises teams
    * to an array of the size provided as the second argument. This constructor 
    * is private as it is intended for use only by the class method loadLeague().
    */
   private League(String aName, Team[] teams)
   {
      super();
      this.name = aName;
      this.teams = teams;
   }

   /* class method */
   /**
    * This method creates a new League object by reading the required details from
    * a CSV file. The file must be organised as follows:
    *     name(String), number of teams (int)
    *     team name(String), won(int), drawn(int), lost(int), for(int), against    (int)
    *        and so on for each team
    * Having created the new League object the method should create all the Team 
    * objects (using the data in the file to set their attributes) and add them 
    * to the teams array.
    */
   public static League loadLeague()
   {
      League theLeague = null;
      String pathname = OUFileChooser.getFilename();
      File aFile = new File(pathname);
      Scanner bufferedScanner = null;

      try
      {
         String leagueName;
         int numberOfTeams;

         String teamName;
         int won;
         int drawn;
         int lost;
         int goalsFor;
         int goalsAgainst;
         Scanner lineScanner;
         String currentLine;
         bufferedScanner = new Scanner(new BufferedReader(new FileReader (aFile)));    
         boolean firstLine = true;
         List<Team> teamsList = new ArrayList<Team>();
         Team[] teams = null;
         while (bufferedScanner.hasNextLine())
         {
            currentLine = bufferedScanner.nextLine();
            lineScanner = new Scanner(currentLine);
            lineScanner.useDelimiter(",");

            if (firstLine) {
                // you originally used "bufferedScanner" which actually 
                // gets the values on the next line, not the current line
                leagueName = lineScanner.next();
                numberOfTeams = lineScanner.nextInt();
                firstLine = false;
                continue;
            }

            Team aTeam = new Team(lineScanner.next());
            aTeam.setWon(lineScanner.nextInt());
            aTeam.setDrawn(lineScanner.nextInt());
            aTeam.setLost(lineScanner.nextInt());
            aTeam.setGoalsFor(lineScanner.nextInt());
            aTeam.setGoalsAgainst(lineScanner.nextInt());
            teamsList.add(aTeam);

         }
         teams = teamsList.toArray(new Team[]{});
         theLeague = new League(leagueName, teams);
      }  
      catch (Exception anException)
      {
         System.out.println("Error: " + anException);
      }
      finally
      {
         try
         {
            bufferedScanner.close();
         }
         catch (Exception anException)
         {
            System.out.println("Error: " + anException);
         }
      }
      return theLeague;
   }

   /* instance methods */

   /**
    * Displays the league table in tabular format to the standard output
    */
   public void display()
   {
      System.out.println(this.name);
      System.out.format("%20s %2s %2s %2s %2s %2s %2s %    2s\n","","P","W","L","D","F","A","Pt");
      for (Team eachTeam : this.teams)
      {
         System.out.format("%20s %2d %2d %2d %2d %2d %2d %2d\n",
                       eachTeam.getName(), eachTeam.getPlayed(), 
                       eachTeam.getWon(), eachTeam.getDrawn(), 
                       eachTeam.getLost(),eachTeam.getGoalsFor(), 
                       eachTeam.getGoalsAgainst(), eachTeam.getPoints());        
      }
   }

   /**
    * Arrange the elements of teams in their natural order. This will only
    * work if a natural order has been defined for the class Team.
    */
   public void sort()
   {
      // to be written later...
   }
}